Fig6_6 Coronal loops

Fig. 6.6 . The corona is stitched together with ubiquitous coronal loops that are created when upwelling magnetic fields generated inside the Sun push through the visible solar disk, the photosphere, into the overlying, invisible chromosphere and corona. These closed magnetic structures are anchored in the photosphere at footpoints of opposite magnetic polarity (marked with + and -). Coronal loops can be filled with hot gas that shines brightly at extreme ultraviolet and x-ray wavelengths. Driven by motions in the underlying photosphere and below, the coronal loops twist, rise, shear, and interact, releasing magnetic energy that can heat the solar corona and power intense solar flares or coronal mass ejections. Large coronal loops are found in the bulb-like base of coronal steamers, whose long, thin stalks extend out into space. Magnetic fields that are anchored in the photosphere at one end can also be carried by the solar wind into interplanetary space, resulting in open magnetic fields and a channel for the fast solar wind.